Arognaute2, a member of the argonaute family of proteins, is the catalytically active component of the RISC that not only facilitates miRNA processing but also their regulatory actions on target mRNA transcripts (Hock and Meister, 2008). In a study by Diederichs and Haber, it was shown that overexpression of Ago2 results in increased miRNA biogenesis (Diederichs and Haber, 2007). Similar to genetic disruption of Dicer, Ago2 deletion results in embryonic lethality in mice, but conditional knock down of Ago2 reveals defects in neural tube closure and mispatterning of the anterior structure of the brain. Mouse embryonic fibroblast (MEFs) isolated from these mutant mice have reduced miRNA expression, which can be reversed by Ago2 expression (Morita et al., 2007). These findings highlight the importance of Ago2 in neuronal differentiation, brain morphogenesis, and development (Liu et al., 2004; Morita et al., 2007).
